In recent years, attention is paid to a silicon optical device formed on a silicon substrate utilizing a silicon electronic circuit fabrication technology capable of implementing large-scale integration at a low cost.
For example, in order to solve the problem of shortage of the communication capacity between chips and between boards predicted in the future from improvement of the performance of an information processing equipment such as a high-performance server, a supercomputer or a personal computer, it is expected to implement a large-scale silicon optical communication device based on a low-loss small-size silicon wire waveguide.
Especially, in order to increase the transmission capacity, it is expected to implement a WDM silicon optical communication device to which a wavelength division multiplexing (WDM) transmission system used for optical fiber communication is applied and which multiplexes a plurality of signal lights having independently modulated wavelengths different from each other in a device and transfers the multiplexed signal lights. Since the WDM silicon optical communication device can multiplex and transmit a plurality of signal lights having wavelengths different from each other into a single transmission path, the transmission capacity (communication capacity) per one transmission path increases significantly and an optical communication device having a smaller size and a greater capacity can be implemented.
It is to be noted that a technology relating to a hybrid laser configured by combining a light emitting device such as a semiconductor optical amplifier (SOA) and a silicon optical device and another technology that converts the spot size by a silicon optical device are available.